Geometry
posted by Abby .
Two supplementary angles are in the ratio 7:11. Find the measure of the smaller angle.

Two Angles are Supplementary if they add up to 180 °
A = smaller angle
B = larger angle
A / B = 7 / 11 Multiply both sides with 11
11 A / B = 7 Multiply both sides with B
11 A = 7 B Divide both sides with 11
A = ( 7 / 11 ) B
A + B = 180 °
( 7 / 11 ) B + B = 180 °
( 7 / 11 ) B + ( 11 / 11 ) B = 180°
( 18 / 11 ) B = 180 °
18 B = 180 ° * 11 Divide both sides with 18
18 B / 18 = 180 ° / 18 * 11
B = 10 ° * 11
B = 110 °
A = ( 7 / 11 ) B
A = ( 7 / 11 ) * 110
A = 770 / 11
A = 70 °
The smaller angle = 70 °